THE IMPACT OF VISUAL AND ULTRASOUND CLASSIFICATION ON THE QUALITY OF WOOD BUILDING ELEMENTS

Abstract

The worldwide demand for sustainable constructions became unavoidable and due to its nature of using renewable material, the wood construction was put in evidence. However, the heterogeneity of the material makes its use as a constructive element difficult, due to the variability of the mechanical properties of the parts. Thus, when designing structural elements, the designer usually indicates two paths: either the increase in the calculated cross sections or in a radical way, specifies another material on which he has more security of its mechanical properties, such as concrete or steel. Thus, with the intention of increasing the potential of the material, this work proceeded to the grading of timber pieces for use in structures. Using non-destructive grading methods NDT (Non-destructive Testing), pieces of structural dimensions with similar mechanical properties were grouped for the composition of panels in two different studies: structural analysis of panels in Cross Laminated Timber- CLT and the study of light longitudinal Shear wood framed walls. This grouping resulted in four levels, and most parts were categorized in class N°3, whose recommendation is to be used in situations that require low stiffness and strength, and the aesthetic factor is not crucial. The non-destructive nature of the procedure allowed the structural parts to be classified at first, visually, and then, through static mechanical testing, obtaining the modulus of longitudinal elasticity in flexion - MOE, for the whole set of parts. The grading carried out in this way allowed the manufacture of CLT and wood frame panels, with similar mechanical properties, enabling the intragroup structural comparison, in the two studies mentioned above.